1. Field of the Invention
The present invention relates to a display device with a built-in panel and a display panel drive method.
2. Description of Related Art
In recent years, plasma display devices with built-in surface discharge method AC-type plasma display panels that constitute large, thin color display panels have attracted attention (see Japanese Patent Kokai No. H5-205642, for example).
FIGS. 1 to 3 show part of the structure of such a conventional surface discharge method AC-type plasma display panel.
Plasma display panels (PDP) are formed having a structure that serves to generate a discharge for each pixel between a front face glass substrate 1 and a rear face glass substrate 4 that are disposed in parallel with each other, as shown in FIG. 2. The surface of the front face glass substrate 1 is the display face. The rear face side of the front face glass substrate 1 is sequentially provided with a plurality of longitudinal row electrode pairs (X′, Y′), a dielectric layer 2 for covering the row electrode pairs (X′, Y′), and a protective layer 3 consisting of MgO (magnesium oxide) for covering the rear face of the dielectric layer 2. As shown in FIG. 1, each of the row electrodes X′, Y′ is constituted by a transparent electrode Xa′ and Ya′, respectively, that consists of a wide ITO or other transparent electrically conductive film, and by bus electrodes Xb′ and Yb′, respectively, that consists of a narrow metal film that supplements the electrical conductivity. The row electrodes X′ and Y′ are arranged alternately in the vertical direction of the display screen so as to face each other with a discharge gap g′ interposed therebetween, where a single display line (row) L of a matrix display is constituted by each pair of row electrodes (X′, Y′). As shown in FIG. 3, the rear face glass substrate 4 is provided with a plurality of column electrodes D′ that are arranged in a direction orthogonal to the row electrode pairs X′, Y′, belt-shaped barrier walls 5 that are formed in parallel between these column electrodes D′, and a phosphor layer 6, which is formed by Red (R), Green (G), and Blue (B) phosphor materials that cover the sides of the barrier walls 5 and the column electrodes D′, is provided. As shown in FIG. 2, discharge spaces S′ in which Ne—Xe gas containing xenon is enclosed exists between the protective layer 3 and phosphor layer 6. Each display line L is formed having a discharge cell C′ constituting a unit light emission region in which the discharge spaces S′ are divided by the barrier walls 5 at the points of intersection between the column electrodes D′ and the row electrode pairs (X′, Y′), as shown in FIG. 1.
As a method for displaying halftones in the image formation of the above-mentioned surface discharge method AC-type PDP, a grayscale drive method that uses subfields is known. In this drive method, a single field display cycle is divided into N subfields, and a number of light emissions that matches the weighting of the subfield is allocated to each subfield. Further, light emission drive is performed by setting subfields in which light emission is implemented for each discharge cell and subfields in which light emission does not take place in accordance with an input picture signal. Here, a middle luminance corresponding with the total number of light emissions implemented via a single field is visualized.
FIG. 4 shows a variety of drive pulses that are applied to the PDP in each subfield in order to implement the drive.
As shown in FIG. 4, each subfield is constituted by a batch reset cycle Rc, an address cycle Wc, and a sustain cycle Ic.
In the batch reset cycle Rc, a reset discharge is performed simultaneously for all the discharge cells as a result of reset pulses RPx, RPy being applied simultaneously between row electrodes X1′ to Xn′ and Y1′ to Yn′, respectively, that together form pairs, and, as a result, a wall charge of a predetermined amount is temporarily formed in each discharge cell. In the address cycle Wc that follows, a scan pulse SP is sequentially applied to the row electrodes Y1′ to Yn′, and a pixel data pulse for each pixel corresponding with an input picture signal is applied to the column electrodes D1′ to Dm′ one display line at a time. That is, as shown in FIG. 4, image data pulse groups DP1 to DPn consisting of m pixel data pulses each corresponding with first to nth display lines are sequentially applied to the column electrodes D1′ to Dm′ in sync with the scan pulse SP. An address discharge (selective erasure discharge) takes place only in the discharge cells to which a high voltage pixel data pulse is applied at the same time as the scan pulse. The wall charge formed in the discharge cells by this address discharge then disappears. On the other hand, the wall charge remains in the discharge cells in which the address discharge has not occurred. In the sustain cycle Ic that follows, sustain pulses IPx, IPy is applied between the row electrodes X1′ to Xn′ and Y1′ to Yn′ that together form pairs in a number corresponding with the weighting of each subfield. Accordingly, the sustain discharge is repeated only in a number corresponding with the number of applied sustain pulses IPx, IPy, only in the light emission cells in which the wall charge still remains. As a result of this sustain discharge, vacuum ultraviolet rays with a wavelength of 147 nm are emitted by the xenon Xe enclosed in the discharge spaces S′. As a result of these vacuum ultraviolet rays, the Red (R), Green (G), and Blue (B) phosphor layer formed on the rear face substrate is excited to generate visible light.
In a display panel like a conventional surface discharge method AC-type PDP, the MgO layer formed on the dielectric layer of the surface substrate comprises a protective function with respect to ion bombardment and a secondary electron discharge function for performing a stable operation by raising the discharge probability. The MgO layer is superior with respect to the a characteristic for discharging secondary electrons during discharge in which the formation face is the cathode, and the discharge probability can be raised. However, because the MgO layer also has an ultraviolet ray absorption characteristic, same cannot be formed on the rear face substrate side (phosphor formation face side). Therefore, in the selective discharge (address discharge) between the column electrodes and scan electrodes of a conventional display panel, the column electrode side on the rear face substrate side is the anode and the scan electrodes on the front face substrate side constitute the cathode, that is, selective discharge is produced by applying a positive data pulse to the column electrodes and a negative scan pulse to the scan electrodes.
The above problems are cited as an example of the problems that the present invention is intended to resolve, an object of the present invention being to provide a display device and display panel drive method that permit an increase in the selective operation to be stably implemented by increasing the discharge probability of the selective discharge.